Rubber goods



March 9, 1943.

, E. L. HANNA RUBBER GOODS ATTO-RNEY curing operation.

- I have found it feasible to use .a dusting mate--- Patented Mar. 9,194-;

UNITED STATES PATENT OFFICE RUBBER GOODS;

Ezra LloydHanna, North 'Scituate, I., assignor to Davol Rubber Company,a corporation of Rhode Island Original application January "2, 1937,serial No.

118,829. Divided and this application September 15, 1941,-Serial No.410,845 a 3 Claims (Cl. 117-139) This application is a division ofapplicationv Serial No. 118,829, filed January 2, 1937, entitledManufacture of rubber goods.

My present invention relates to the manufeature of rubber goods, and hasparticular reference to the formation ofthe surface thereof.

Rubberarticles designed for medical use reduire clean surfaces, free ofany foreign matter. If the surface is exposed, it is comparativelysimple to free the surface of any extraneous matter, and to sterilizethe article for-use. It is, however, diflicult to free an inner surface,as for I have also found that the inner surfaces of rubber articlesshould not be exposed to the 3 atmosphere in the curing oven, as thetemperaturechangesinduce a flow of air therein and therethrough whichincludes dust particles. In

curing tubes, it is preferred to close'both ends,

and to provide a vent at one end; thus, referring to Fig. .3, the tubel2 has one end I 3 closed, as

example the interior of an intravenous tube, from sists of a novelarrangement of parts more fully disclosed in the detailed descriptionfollowing, in conjunction, with the accompanying drawing, and morespecifically pended thereto. a I

In the drawing:

Y Fig. 1 is a plan-view of an illustrative rubber article having. aninner surface, the figure showing a tube; r

Fig. 2 is a view of one end, broken away and spread to disclose thesmooth interior surface; and i m The manufacture ofv rubber articleshaving inner surfaces, such as tubes, involves the prev'ention ofadhesion during. handling, the'pr'eferred procedure utilizing a dustingpowder, and the removal of the dusting powder and of ex-. traneousforeignmatter, such as dust, afterthe rial which will effectivelyprevent adhesion of tacky rubber surfaces, and which combines with thesurface rubber during the curing operation to become an integral partthereof and to impart -a smooth, glassy finish to the surface.

defined in the claims ap- J Fig. 3 is a plan view showing the preferred,arrangement during curing.

. dust-free and ready for sterilization and immediate use.

I have found that the stearates and oleates of certain metals,forexample zinc, magnesium and calcium, have this property, the preferredmate,-

. rial being zinc stearate. Thesecompounds are excellent as dustingpowders, and are absorbed by the rubber during the curing operation, the

resulting surface being smooth, glassy, and absolutely'clean. Thus, see'Figs. '1 and 2, the tube by means of a clip I4, and the other end i5 isalso'closed, as by means of aclip IE, but has a small vent tube, llsecured therein, whereby the expanded air in the tube, during thecuring, may freely exit. Since there is no circulation through the tube,and the dusting wder is absorbed in the-inner rubber surface, thecompleted tube is Although I have described my invention with specificreference to rubber tube manufacture, I it is clear that the inventionmay be applied to the manufacture of any rubber article, andparticularly article having inner surfaces, and that any suitablematerial maybe used as a'coatin'g material for the surface thereof,which hasthe properties of. preventing adhesion during handling andprior to curing, and of being absorbed by the rubberduring the curing,.so as to be completely removed.

A dustingpowder such as described has an" additional advantage when usedwith rubber articles which are acid cured, as for example in an acidsulphur chloridesolution or vapor, as a.

surface coating of the dusting powderreacts with the solutionor vapor,or is affected during the vacid cure, so as to increase the translucenceof the rubber articles; similarly, the transparency of transparentrubber articles; and particularly of dipped articles, is heightened. Thenovel dusting powder thus possesses important advantages over starch,talcor mica dustingpowders, which do not affect the surface conditions.

While specific dustingpowders have been described, the materials ortheir equivalents may be in theform of paste or liquid, if desired, toobtain the proper surface conditions. I claim:

1. A rubber-tube having a smooth, glassy inner .surface, said surfacehaving absorbed therein during curing a salt of a fatty acid selectedfrom the group consisting of calcium oleate and zinc stearate.

2. A rubber tube having a smooth, glassy inner surface having absorbedtherein zinc stearate during curing.

ID has a smooth inner surface ll after curing,

3-. Arubber tube having a smooth, glassy inner surface having absorbedtherein calcium oleate during curing.

